The invention relates to glue applicators that dispense hot, melted glue for general purpose bonding.
Typically, glue applicators have a gun-like shape with a handle portion and a barrel portion. A trigger actuated mechanism in the handle portion moves glue towards a heating chamber in the barrel portion. The glue usually comes in a cylindrical form and is breech-loaded into the glue applicator. A heater in the heating chamber melts the glue which has been advanced by the trigger actuated mechanism. The melted glue is then forcibly extruded from a nozzle or tip at the end of the barrel portion onto the desired location. The nozzle or tip diameters are usually about 0.65 inches in diameter or larger.
One of the problems with prior applicators is with the form of the glue being used. Typically, standard household and light duty commercial applicators use polyamide glue in the form of a 0.25, 0.31 and 0.44 inch diameter round or oval sticks. The sticks of glue used in these applicators are available in various lengths usually ranging between about two inches to ten inches. The use of longer sticks of glue results in less frequent refilling, but render the applicator unwieldy because a large portion of the glue stick hangs out the back of the applicator. This unbalanced condition adds an element of clumsiness to the manipulation of the applicator during glue application. As a result, accurate placement and control of the glue is more difficult and the wrist and hand of the user is more stressed. The use of shorter sticks of glue makes the applicator easier to handle and manipulate, but requires frequent reloading because the glue runs out more quickly.
Another problem with prior glue applicators is that once the glue is heated, but not being applied, the glue can dribble out of the tip onto the work surface, creating a mess. When the applicator is lifted, the glue xe2x80x98stringsxe2x80x99xe2x80x94that is, forms thread-like strands of glue that set-up immediately in the cooler air. The large blob of semi-liquid glue present at the tip continually xe2x80x98feedsxe2x80x99 the thread creating a mess on the work piece and the work surface. Even glue applicators equipped with a check valve to control dribble are subject to this phenomenon.
Yet another problem with prior glue applicators is what to do when the applicators are not being used to dispense glue, but will be used again shortly, i.e the glue in the applicator has been advanced to the heater and is melting or melted, but is not being dispensed. Some applicators have a wire bale that rotates down from under the tip to provide a precarious three-point stance with the butt of the handle. This technique does support the applicator, but does so in a very precarious manner. The applicator can readily tip over, especially when longer sticks of glue are used in the gun. Additionally, even when the tip is supported by a wire bale, the glue can still dribble out onto the work surface creating a mess. The mess is further compounded if in a subsequent operation the applicator is placed back into a puddle of dribbled glue. Some applicators have no support features whatever and are simply laid on their side.
Yet another problem with prior glue applicators is that relatively high wattage heaters are needed to melt the glue. These higher wattage heaters are more expensive, require more power, still take a while to melt the glue, and generate a volume of heat which can be hazardous to the operator. Typically, a 40 watt heater is used in these prior applicators. Warm-up from room temperature to application temperature for glue in an applicator using 0.44 inch diameter round stick of glue with a forty watt heater can take up to eight minutes because of the shear volume of glue that must be heated. A few applicators which utilize 0.25 and 0.31 inch diameter xe2x80x9clow temperaturexe2x80x9d sticks have more economical, lower wattage heaters in the ten to twenty watt range, however even these heaters are still expensive, require more power than is necessary, still take a while to melt the glue, and generate a volume of heat which can be hazardous to the operator.
An applicator for glue in accordance with one embodiment of the present invention includes a glue dispensing assembly and a housing with a barrel section, a handle section and a base. At least a portion of the glue dispensing assembly is located within the housing. The barrel section is adjacent to one end of the handle section and the base is adjacent to another end of the handle section. The base supports the handle section and the barrel section above a surface when the base is placed on the surface.
An applicator for glue in accordance with another embodiment of the present invention includes a glue dispensing assembly, a housing with a barrel section, a handle section, and a base, and a removable container. At least a portion of the glue dispensing assembly is located within the housing. The barrel section is adjacent to one end of the handle section and the base is adjacent to another end of the handle section. The removable container for housing the glue to be dispensed is located at least partially within an opening in the base of the housing.
An applicator for glue in accordance with another embodiment of the present invention includes a housing, a glue dispensing assembly located at least partially within the housing and glue located in the housing where the glue has a filament form factor of greater than about 100.
A replaceable container of glue for use in an applicator in accordance with yet another embodiment of the present invention includes a container housing with glue having a filament form factor of greater than about 100.
One of the advantages of the present invention is that the applicator provides a stable and convenient base to rest on a surface and support the handle and barrel sections of the applicator when in operation, but not dispensing glue. Additionally, the base supports the applicator in a manner making it easy to grasp and continue using the applicator. Further, by locating the removable container which houses the coil of glue in the base, weight is added to the base which promotes even more stability.
Another advantage of the present invention is that the applicator is designed to minimize the amount of glue which dribbles out and to control where any glue that dribbles out may land. The applicator includes a check valve to minimize the volume of glue dribble volume and a nozzle with a 0.04 inch diameter or smaller hole to minimize glue volume available for the stringing phenomenon. Additionally, the tip or nozzle of the applicator is designed to stay within the outer periphery of the base when the base is resting upon a surface. As a result, any glue which does dribble out will drip onto the base of the applicator, not on the work surface. Preferably, the base is constructed of a material which can be easily cleaned.
Another advantage of the present invention is that the applicator uses a lower wattage heater. The applicator melts glue at the same temperature as existing models, but because the volume of glue to be melted is far less, a small wattage heater can be used. This saves energy and keeps the radiated and conducted heat to a minimum. Because of the relatively small thermal mass, the operator""s hand can get closer to the dispensing point at the tip, thereby increasing precision of the application. (One""s hand can be quite close to the flame of a wooden match, but must be much farther away from a log burning in a fireplace. Both fires are burning at the same temperature, but the amount of heat energy is quite different.)
Another advantage of the present invention is that the applicator uses glue having a filament form factor of greater than about 100. Filament form factors are discussed in greater detail below. With a filament form factor of greater than about 100, the glue can be easily coiled and stored in a replaceable container which can be easily snapped into place into the applicator. Additionally, since the glue can be coiled, a large amount of glue can be stored within the applicator for use. As a result, the operator can use the applicator for a much longer period of time without running out of glue. Further, the thinner glue takes less time and energy to heat to a melting point. Even further, the smaller volume of glue being dispensed enables the operator to more precisely dispense glue.